A constant problem for the user of any visually aimed device, such as a pistol, rifle, bow and arrow, etc. having "open" sights (a front sight member and an axially spaced rear sight vane), has been focusing the aiming eye between the rear sight vane, the front sight, and the target. Because of relative spacing between the three objects, this is physically impossible. At best, only one of the objects can be in focus at a time. Thus it is usually necessary to allow the rear sight vane to become blurred due to its proximity to the eye. The front sight or the target then must also become blurred. This system is at best a compromise.
Telescopic sights represent a vast improvement over "open" sights by producing an enlarged erect image of the target to the aiming eye. "Cross hairs" built into telescopic sights indicate the point of projectile impact on the target. The cross hairs and enlarged target image both appear in focus if the optics are properly adjusted.
An optical non-telescopic sight for hand guns is produced by Precision Reflex Inc., P.O. Box 95, New Breman, Ohio 45869 in which an optical system is used in an open ended tube along with a "cross hair" reticle. There is no magnification involved, and the cross hair is used as the only reticle centered on the target. The front sight does not become involved, as both front and rear sights are replaced by the cross hair. The device is relatively compact and easily mounted to small weapons such as pistols for improved sighting purposes.
Most optical sights such as the telescopic sights described above have several drawbacks. They increase the bulk and weight of the weapon; they are relatively easily damaged; they are often as expensive as the weapon itself; they are at times subject to weather conditions (fogging in cold weather); and they typically eliminate the use of the old "open" sight system as an alternative when placed on weapons having existing sight systems. Another difficulty with telescopic sights is the reduced field of vision presented to the shooter. It is often very difficult to adjust between normal vision and telescopic vision. The result is that the target is often lost through a telescopic lens when it is easily visible to the naked eye.
The field of vision problem is improved by lower power telescopic sights. The "Precision Reflex" pistol sight, since it has no magnification power, presents no field of vision problem. However, the cross hairs are used as the sole reticle and accuracy may be severely affected if the cross hairs are not centered (by the shooter's eye) within the tube at the time of firing.
Aperture or "peep" sights make use of a rear sight "disk" with a small aperture which defines a circular opening. The front sight post is "centered" in the apertured disk for sighting purposes. These sights have the advantage over usual "iron" sights in that the rear sight disk can be somewhat ignored by the aiming eye so only the front sight and target need be focused on. An example of an aperture or "peep" sight is disclosed in the 1931 U.S. Pat. No. 1,834,248 to Lorenzen. Lorenzen also discloses a "peep" type front sight. Sighting techniques used by the Lorenzen sight arrangement are similar to those typically used for aperture sights. Use of this type of sight depends significantly on the eyesight of the shooter. The small diameter opening can also become fouled. However, the principal disadvantage is that for efficiency the aperture must be located as close to the aiming eye as possible. Because greater accuracy is possible with close disk-eye distances, effective use of "peep" sights is limited by the recoil of high power rifles and the very nature of pistols (which must usually be held at arm's length).
Another difficulty with open sights is discovered when it is necessary to aim at a target beyond the range at which the sights were initially set. Accommodation must be made by raising the projectile trajectory. This can be done with some weapons by elevating the rear sight so the muzzle has to be raised to bring the front sight into proper alignment. The elevation of the eye must also be elevated with respect to the weapon, often to the discomfort of the shooter. The other alternative is to hold the rear sight at the same elevation and raise the front sight (along with the muzzle of the weapon). This is not done because the front sight quickly obscures the view of the target.
Optics have been used with limited success in sight systems. Shooters with failing eyesight can fit their weapons with prescription ground "peep" sight disks. One such device is disclosed in U.S. Pat. No. 1,964,927 granted in 1934 to F. E. Bliss. The Bliss sight combines a standard "peep" sight base with a circular prescription ground lens as the disk aperture. The lens provided is used merely to correct for vision defects of the shooter. The device does not substantially change the normal sighting procedure. It merely does away with the need for the shooter to wear glasses or other optical corrective devices when shooting. A front sight arrangement shown in the Bliss patent includes extra front sight posts spaced laterally of the conventional center post. These sights can be used for "leading" a moving target. Range adjustments are made in the usual way; by raising or lowering the rear optical sight.
U.S. Pat. No. 2,906,160 granted in 1959 to Palley describes a range finding sight device that makes use of a specially ground optical lens coupled with an axially spaced pair of cross hair reticles. In sighting with the device, the proper cross hair arrangement must be selected and aligned with the target through the lens. Since the cross hairs are behind the lens, the same focusing problem exists as with open sights, only to a somewhat reduced degree due to the relative proximity of the spaced cross hairs. It is important to note that the lens is a convex-concave type with a positive diopter value for off-setting the image of the target, not the front sight. The normal front sight of the weapon is not used. It is replaced by the front set of cross hairs directly behind the lens. The only function of the positive diopter value of the lens is in selecting a range sighting adjustment that does not require physical movement of the sights relative to the weapon.
U.S. Pat. No. 2,420,252 to E. H. Land granted in 1947 discloses an interference sight for guns, cameras, etc. that accommodates varying angular positions between the shooter's eye and the sight reticle. The single reticle is the only one provided (as with standard telescopic sights) so two axially spaced sights needn't be aligned for sighting purposes. It is further disclosed that the reticle is impressed on the shooter's field of view at optical infinity. The reticle therefore remains in focus with the target. Also, the reticle is an image rather than a real object. Due to the physics of the lens, the reticle will "move" within the confines of the lens when the angle of the shooter's eye changes. This can be done without significantly changing the point of impact for the projectile. Again, it is pointed out that the front sight is eliminated completely, with accuracy depending entirely upon positioning of the reticle with respect to the projectile trajectory. Land discloses that range adjustments can be made with his interference sight by gauging distances between interference rings that appear in the sight image.
The range problem discussed above becomes more acute with short range weapons such as bows and other arrow or heavy projectile launching devices. Extreme angular changes in the initial projectile axis must be used for increasing range distances. Typical bow sights must therefore become rather bulky and complex to accommodate the wide range of angular positions at which the weapon must be fired in order to maintain reasonable accuracy. An excellent example of such a sight is disclosed by Crook in U.S. Pat. No. 3,027,648 granted in 1962. Crook's archery sight includes several mechanical adjustment features for setting a single sight post or reticle to compensate for distance, wind, etc.
A substantially simpler device is disclosed by Steiber, in the 1951 U.S. Pat. No. 2,574,599. Steiber uses a single upright notched plate as the front sight reticle for bows. The rear "sight" is comprised of a "bead" on the bow string. When the bow string is fully drawn, the bead is located very close to the aiming eye and is therefore out of focus with the target and front sight.
The need therefore remains for a sight system that does not produce the focus disadvantage of open iron sights, the range adjustment of and eye proximity problems of aperture sights, the multiple disadvantages of telescopic sights, and the accuracy difficulties presented with single reticle sights that have all remained basically unimproved until the advent of the present invention.
The present sight arrangement represents a remarkable improvement over any known form of general use sight. By making use of an axially spaced visual image aligned substantially parallel to the projectile axis, the present sight offers an unquestionable sight "picture" and a corresponding high degree of accuracy. Accuracy is significantly enhanced by visual magnification of the perceived image of the front sight member. Slight movement of the front sight member is also magnified so the user might become more aware of such movement and take steps toward correction. The front sight is an "image" within the rear sight lens and, as such, will "disappear" progressively as the image is raised or lowered out of the field of view for the lens. This feature is significant in that range adjustments can be made merely by raising or lowering the discharge angle of the device without the need for making physical sight adjustments. The lens used in the rear sight of the present invention is inexpensive to manufacture and can be mounted to a wide variety of firearms or other visually aimed devices. This can be done without obscuring the normal function of existing sight arrangements since the present lens structure can be positioned clear of the existing line of sight used for any existing sight system, including open, aperture, or telescopic sight systems. Either one of the two systems can therefore remain as an auxiliary sight system should the other system become unusable.